Sark (full program name SARK-ES-1117821), written by Ed Dillinger, was the commander of the MCP's army and overseer of the games fought on the Game Grid. He was a merciless and evil program, willing to do anything that pleased the MCP. Sark was in charge of forcing the programs that believed in the users to play video game type gladiator games with personnel from Sark's Army as the opponents. He looked forward to playing the gladiator games when he had the chance. So ruthless was Sark that he was described as "Brutal and Needlessly Sadistic" by the MCP himself.

When Kevin Flynn was brought into the Game Grid for "pushing" the MCP in the real world, Sark expressed some apprehension to squaring off against a user. The MCP tortured Sark until he saw his leader's point of view and instructed him that Flynn was to be in the games until he dies playing.

During the a light cycle match, when Flynn, Tron, and Ram all escaped the game grid, Sark relentlessly pursued the renegades, his Light Tanksderezzing Ram. Sark was instructed to round up the remaining renegade programs and bring them to the MCP. With all his enemies in one place, the MCP felt a presence on the Mesa outside its core, Tron. Sark went forward to deal with the program saying that Tron should have joined his ranks because they would have "made a great team."

After a fierce disc battle, Sark suffered a mortal blow from Tron that was so powerful the Commander's own disk was split in two trying to block the shot. Tron's disc cut right through Sark's head and scalped him.

Sark was saved and resurrected by the MCP, who granted him all of his functions to stop Tron. As Sark and Tron battled, Flynn jumped into the MCP's communication beam distracting the MCP long enough for Tron to get his disc in. Sark was derezzed when his master perished.

Trivia

Sark's first death is considered one of the most graphic deaths to occur in a Disney film as his brain becomes completely exposed after Tron's Identity Disc cuts through his skull.

The director of the original TRON felt guilty casting a British actor as the main villain in the film. However, he was satisfied with David Warner's performance and talent.

His speech to the new conscripts is repeated in part nearly word-for-word in the Armory of the disc arena as Sam Flynn is given his Identity Disc.

Clu commands Rinzler to "Finish the game!" when ordering him to take the killing shot at the Flynns and Quorra - the same command Sark gives to programs who refuse to end their opponents' lives on the Game Grid.